Feed collet



E. E. MINARD v FEED GOLLET Filed April 15. 1925 Patented 0a. 25, 1927.

UNITED STATES.

ERNEST E. MINARD, OF DETROIT, MICHIGAN.

FEED COLLE'I.

Application filed April 13, 1925. Serial No. 22,749.

This invention relates to feed collets used in automatic and hand-operative screw-machine, bar-forming machine, and the like for feeding stock so thatv end or intermediate portions of the stock maybe operated upon for the production of screws and other articles of manufacture. A feed collet is adapted to intermittently advance the stock and a well known type of collet includes resilient fingers formed from a tubular piece of material and adapted to have the finger ends frictionally grip .a piece of stock and advance it axially of the tubular piece of material.

My invention has special reference to that class of collets wherein the finger ends are provided with detachable and interchangeable pads 0r gripping aws, and in this class of collets some trouble has been experienced by the pads or jaws becoming displaced when a piece of stock encounters the same.

The primary object of my invention is to provide a set of pads or jaws for a collet with positive and reliable means, as hereinafter set forth, for preventing endwise displacement -of the pads orjaws when encountering a piece of stock.

' Another object of this invention is to provide collet jaws with means for preventing circumferential shifting of the jaws in a collet, said means having an engagement with the collet fingers that does not interfere with the resiliency of the fingers nor weaken the same to the extent of decreasing the efficiency of the collet.

The above are, a few of the objects attained by my improvement and others may appear as the nature of the invention is better understood byreference to the drawing, wherein Figure 1 is a side elevation of the collet, partly broken away and partly in longitudinal section;

Fig. 2 isa cross sectional view taken on the line H-H of Fig. 1;

Fig. 3 is a cross sectional view of the collet showing the manner of forming opposed openings in fingers of the collet;

Fig. 4 is a side'elevation of a set of pads or jaws for the collet; and

Fig. 5 is an end view of the same.

lln the drawings, the reference numeral 1 denotes a collet adapted to be placed in a machine and reciprocated therein to intermittently feed a piece of stock 2. The collet 1 is formed from a cylindrical body or tube longitudinally slitted, as at 3, to provide opposed resilient fingers 14.

Adjacent the outer end of the collet are opposed arcuated slots 4 disposed transversely of the fingers and extending through the fingers with the outer ends of the slots of less area than the inner ends, this being brought about by using a rotary cutter or other instrumentality 5 to form the slots. The rotary cutter may be placed in the end of the collect and moved first into engagement with one finger 14 and then the other finger, as brought outin Fig. 3, thus producing the slots with parallel side walls and curved end walls, the curved end walls being designated 6 and curving inwardly from the inner walls of the fingers 14: to the outer walls thereof.

Mounted in the outer end of the collet is a set of opposed pads or jaws 7, each substantially semi-cylindrical to form a assage 8 for the. piece of stock 2 whic is adapted to be frictionally engaged by the pads or jaws to be advanced when the collet is shifted in afeeding direction, the pads or jaws sliding on the piece of stock to obtain a fresh purchase or grip thereon when the collet recedes for such purpose.

The inner ends of the pads 7 are beveled inwardly from the outer cylindrical wall of the pa d to the inner wall thereof, as at 9 so that these beveled walls may cooperate in providing a sloping easy entrance into the passage 8 for an end of the stock 2, thus preventing the pads from receiving an end blow that would tend to force the the outer end of the collet.

On the outer cylindrical walls of the pads 7 are substantially crescent shaped lugs or abutments 10 adapted to extend into the slots 4 and substantially fill said slots, said lugs having side walls or shoulders 11' and curved end walls 12, the side walls or shoulders 11 preventing longitudinal movement of the pads in thecollet and-the end walls 12 preventing circumferentially shifting of the pads. The lugs 10 have an arcuated length approximately half the semi-circumference of each collet finger, such being in contradistinction to any shoulder or abutment that is semi-circular or semi-cylindrical, for it is obvious that the slots 4 could not be made completely semi-circular. In cuttin the slots 4 throu h the fin ers 1d there is a maximum dept for the u s 10 efiective for preventing longitudinal s iftpads from ing of the pads, and'while there is a maximum inter-engagement between the pads and the fingers, yet the outer Walls of the fingers are not interrupted and cannot interfere with any reciprocation of the col'et.

In practice the lugs 10 will snugly fit in the slots 4 but, if. for any unforeseen reason the lugs should become loose in the slots 4: one pad will simply approach the other and not become fully disengaged from its finger, because of the proximity of the longitudinal edges of the pads. Should'one of the pads fall on to the other the lug 10 of the fallen pad still extends into the slot 4 of its finger and a piece of stock encountering the beveled ends 9 of the pads will simply raise the fallen pad and establish the proper relation between the pad and its finger for an operative action of the collet as a feeding device.

1 The abrupt deep side walls or shoulders 11 of the lugs 12 are essential to prevent any endwise slippage of the pads and it is by virtue of these side walls or shoulders that it is practically impossible for a piece of stock to force the pads endwise from the outer end of the collet. It is obvious that the pads are interchangeable for stock of various diameters or cross sectional shapes and that the mounting of-.the pads within the outer end of the collet does not interfere with the resiliency of the fingers 4 in functioning as stock feeding means.

' There are various ways of producing the lugs 10 on the pads 7 and in practice I prefer to machine the outer walls of the pads for accurate formation of the lugs, so that there will be a positive interlocking of the pads and collet fingers. I In view -of this practice, a method is involved which consists in internally cutting collet fingers to provide opposed open slots, and i then machining the outer walls of pads to form lu s adapted to snugly fit in the slots of the collet fingers, one pad being first placed in position and then the other, so that the pads are positively retained within the collet against accidental displacement by a piece stock contacting therewith.

It is thou ht that the utility of my invention will %8 apparent without further description, and while in the drawing there is illustrated a preferred. embodiment of my invention, it is to be understood that the structural elements are susceptible to such variations and modifications as fall within the scope of the appended claims.

What I claim is I 1. A feed collet having opposed resilient fingers formed with slots, and pads between said fingers and backed up against outward radial movement by the finger walls. said pads being formed with transverse abrupt shoulder portions for engagement with side walls of said finger slots.

. 2. A feed collet slitted to provide opposed resilient fingers, each finger having a slot adjacent the outer end thereof, opposed pads in said collet providing a stock passage having a beveled entrance, saidipads having walls flush with the slit walls 0 the fingers,

and means on said pads extending into and filling the finger slots to prevent longitudinal and circumferential shifting of said pads relative to said fingers.

3. A feed collet as called for in claim 2, wherein said pads are non-yieldable in an outward radial direction and said means has a configuration which may permit said pads to move towards each other without disengagement from said fingers to the extent of permitting longitudinal shifting of the pads relative to said fingers.

4:. A feed collet as called for in claim 2, wherein said means'is in the form of lugs having abrupt deep side Walls engaging similar walls of said finger slots.

5. A feed collet comprising resilient fin- Igers, pads set against the inner walls of said ngers and free to move inwardly towards each other, and abrupt shouldered lugs preventing longitudinal displacement of said pads relative-togsa'id fingers.

' 6. A feed collet as called for in claim 6 wherein said lugs are radially disposed relative to the axis of said collet.

In testimony whereof I affix my signature.

. ERNEST E. MINARD. 

